1. Field of the Invention
This invention relates to a color solid image pickup element which comprises a semiconductor chip and a color filter bonded to the semiconductor chip.
2. Background of the Invention
A color solid image pickup element formed by bonding a color filter on a semiconductor chip is well known in the art. More specifically, the color solid image pickup element is manufactured as follows. A color filter layer is formed on a supporting substrate such as a glass plate. The assembly of the color filter layer and the substrate is subjected to dicing to provide a color filter in the form of a chip. The color filter thus provided is bonded with adhesive to the surface of a semiconductor element in the form of a chip.
In general, the color filter layer is a gelatin or casein emulsion layer or an organic film coating, the material of which is a mixture of resin and a coloring agent. Therefore, the color filter layer is softer than the components of the semiconductor element.
On the other hand, in the case where the color solid image pickup element is made up of the color filter layer of the aforementioned organic film coating, sometimes its spectral characteristic is unsatisfactory depending on the purpose of use. In order to overcome this difficulty, the following method is extensively employed. As shown in FIG. 1, an interference film filter 2 having a multi-layer structure is formed by using separate SiO.sub.2 or TiO.sub.2 dielectric layers 1 according to the desired color. The filter 2 thus formed is bonded to the surface of a semiconductor element 3.
As was described above, the assembly of the color filter layer and the substrate is diced to form the color filter in the form of a chip. The color filter layer of the color filter thus formed is bonded to the surface of the semiconductor element. However, prior to the bonding operation, it is necessary to wash the color filter because foreign material such as glass shavings might have stuck to the color filter in the dicing operation.
However, even if the color filter has been washed, often the foreign material remains on the surface of the filter, thus damaging the surface of the semiconductor element when the color filter is bonded to the semiconductor element.
In the case where the color filter layer is the organic film coating as was described above, the color filter layer is softer than the semiconductor element, and therefore when the color filter is bonded to the surface of the semiconductor element, the foreign matter such as glass shavings, entering the color filter layer, will not damage the surface of the semiconductor element. On the other hand, in the case of the interference film filter, the color filter layers are, in general, substantially equal in hardness to the glass substrate. Therefore, when the filter is bonded to the semiconductor element, the foreign material which impinges the semiconductor element damages the surface of the latter.